Heat dissipation heat sink

Abstract

The thermal dissipative heat sink (800) includes a cold plate (806), a radiator (880) attached to the cold plate, and a thermal compound (882) disposed between a heat source (830) and the cold plate (806) and coupling the heat source to the cold plate, the thermal compound (882) converting a portion of a first phononic thermal energy from the heat source into a first photonic near-field thermal radiation and a first photonic far-field thermal radiation, and transferring the first photonic near-field thermal radiation, the first photonic far-field thermal radiation, and the remainder of the first phononic thermal energy from the heat source to the cold plate (806). The cold plate (806) couples the first photonic near-field thermal radiation, the first photonic far-field thermal radiation, and the remainder of the first phononic thermal energy from the heat source into a second phononic thermal energy and provides the second phononic thermal energy to a radiator (880). The radiator (880) converts the second phononic thermal energy into the second photonic near-field thermal radiation and the second far-field thermal radiation and emits the second photonic near-field thermal radiation or the second photonic far-field thermal radiation to regenerate the cold plate (806).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 299,187, filed January 13, 2022, the contents of which are incorporated by reference in their entirety herein. [Background technology]

[0002] Photons and phonons are the two fundamental carriers of thermal energy in and between matter. Photons are thermal excitation waves of electromagnetic fields, and phonons are waves of oscillatory atomic kinetic vibrational energy. Photons can be classified as those that exist in the near field (NF) of a source (i.e., photons that exist as excitations of the electromagnetic field within one wavelength of a surface) or those that exist in the far field (FF) of a source (i.e., photons that exist as excitations of the electromagnetic field beyond one wavelength of a surface). Photons and phonons together give rise to thermal radiation. This thermal radiation corresponds to the conversion of thermal energy into electromagnetic energy, and thus to the emission of electromagnetic waves (propagating as excitations in the electromagnetic field) from an object due to its temperature.

[0003] All objects with a temperature above absolute zero emit thermal radiation in a spectrum of wavelengths. Infrared radiation, or infrared electromagnetic waves, is a part of the electromagnetic spectrum that includes near infrared (NIR), which has wavelengths from about 0.8 to 3 μm and is closest to red visible light, mid infrared (MIR), which has wavelengths from about 3 to 14 μm, and far infrared (FIR), which has wavelengths from about 14 to 30 μm and is closest to microwaves.

[0004] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. Summary of the Invention

[0005] The heat sink coupled to the heat source includes a cold plate having a thermal reservoir, a radiator attached to the cold plate, and a thermal interface material disposed between the heat source and the cold plate and coupling the heat source to the cold plate. The thermal interface material is configured to convert a first phononic thermal energy from the heat source into a first photonic near-field thermal radiation and a first photonic far-field thermal radiation, and to transfer the first photonic near-field thermal radiation, the first photonic far-field thermal radiation, and a remainder of the first phononic thermal energy from the heat source to a bulk material of the cold plate. The bulk material of the cold plate is configured to convert the first photonic near-field thermal radiation, the first photonic far-field thermal radiation, and a remainder of the first phononic thermal energy from the heat source to a second phononic thermal energy and provide the second phononic thermal energy to the radiator. The radiator is configured to convert the second phononic thermal energy into a second photonic near-field thermal radiation and a second far-field thermal radiation and emit the second photonic near-field thermal radiation or the second photonic far-field thermal radiation to continuously regenerate a thermal reservoir of the bulk material.

[0006] A heat sink coupled to a heat source includes a radiator configured to emit super-Planckian photonic near-field and far-field thermal radiation from the heat source, the radiator comprising a photonic crystal made of a refractory material. The photonic crystal comprises a plurality of beams arranged in a woodpile configuration. The unit cell comprises four layers of beams having diamond lattice symmetry. The radiator is configured to accumulate the super-Planckian photonic near-field and far-field thermal radiation in a working fluid.

[0007] The heat sink coupled to the heat source includes a cold plate including a bulk material having a thermal reservoir, a radiator attached to the cold plate, and a compound disposed between the heat source and the cold plate and coupling the heat source to the cold plate. The radiator includes a photonic crystal, the photonic crystal including a plurality of beams arranged in a woodpile configuration. The four layers of beams include a unit cell having diamond lattice symmetry. The thermal compound is configured to generate super-Planckian thermal radiation from the heat source, the super-Planckian thermal radiation being absorbed and transmitted by the bulk material of the cold plate. The radiator is configured to emit super-Planckian near-field thermal radiation and super-Planckian far-field thermal radiation, such that the thermal reservoir of the bulk material is continuously regenerated.

[0008] This Summary has been provided to introduce in a simplified form some of the concepts that are further described in the Detailed Description below. This Summary is not intended to determine key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the disadvantages noted in the Background. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram of a portion of the electromagnetic spectrum including the transmittance of a subset of electromagnetic energy at various wavelengths. [Diagram 2] FIG. 2 illustrates a perspective view of a passive thermal dissipation heat sink configured to couple to a heat source in one embodiment. [Diagram 3] FIG. 3 is a schematic diagram of the passive heat dissipation heat sink device of FIG. 2. [Figure 4] FIG. 2 is a schematic diagram of a passive heat sink device in another embodiment. [Diagram 5]5(a) and 5(b) are example diagrams of a thermal metasurface configured on the upper planar surface of the emitter face of a concentrator rod. [Figure 6] FIG. 2 is a schematic diagram of a passive heat sink device in another embodiment. [Figure 7] FIG. 1 illustrates a perspective view of a passive thermal dissipation heat sink device with interacting stacked fins in one embodiment. [Figure 8] FIG. 2 is a perspective view of a passive thermal heat sink device having non-interacting stacked fins according to an embodiment. [Figure 9] FIG. 2 is a schematic diagram of a passive thermal dissipation heat sink device in an embodiment. [Figure 10] 1 is a schematic diagram of an exemplary liquid cooling system in the prior art. [Figure 11] FIG. 1 illustrates a perspective view of an embodiment of a passive heat sink device having a liquid cooling system. [Figure 12] FIG. 1 is an exploded diagrammatic perspective view of a passive thermal heat sink device having a photonic crystal according to an embodiment. [Figure 13] FIG. 1 is a perspective view of a woodpile photonic crystal radiator according to an embodiment. [Figure 14] FIG. 14 is a side view of FIG. 13. [Figure 15] FIG. 2 is a schematic diagram of an active thermal dissipation heat sink device in an embodiment. [Figure 16] FIG. 2 is a schematic diagram of an active thermal dissipation heat sink device in another embodiment. [Figure 17] FIG. 13 is a schematic diagram of an active thermal dissipation heat sink device in yet another embodiment. [Figure 18] FIG. 1 is a diagram of an enclosure having a thermal dissipative heat sink utilizing a series of infrared reflective mirrors to route thermal radiation in a line-of-site configuration in one embodiment. [Figure 19] FIG. 1 illustrates an embodiment of multiple enclosures with a dissipative heat sink utilizing a series of infrared reflective mirrors to route thermal radiation in a line of sight configuration. [Figure 20] FIG. 2 is a schematic diagram of multiple enclosures, each having a thermal dissipation heat sink coupled to a light channel enclosure, in one embodiment. [Figure 21] 21 is a perspective view of an embodiment of a server rack configured to house multiple server casings, which are not shown for clarity. [Figure 22] 22 is a perspective view of an embodiment of a server rack configured to house multiple server casings, which are not shown for clarity. [Diagram 23] 23 is a perspective view of the server rack of Figures 21 and 22 including multiple server casings, with one server casing omitted for clarity, according to one embodiment. [Figure 24] FIG. 1 is a perspective view of a dispersive radiative server room or data center including a plurality of server racks configured to house a plurality of server casings according to one embodiment. [Diagram 25] FIG. 1 is a perspective view of an adaptive optics radiative server room or data center including a plurality of server racks configured to house a plurality of server casings in another embodiment. [Figure 26] FIG. 1 is a perspective view of an aggregate radiative server room or data center including a plurality of server racks configured to house a plurality of server casings in another embodiment. [Figure 27] FIG. 23 is an enlarged cutaway view of one optical coupling shown in FIGS. 21 and 22 in one embodiment. [Figure 28]FIG. 2 is a schematic diagram of a passive thermal dissipation heat sink device in an embodiment. [Figure 29] FIG. 1 is a schematic diagram of a server enclosure including a passive thermal dissipation heat sink device according to an embodiment. [Diagram 30] FIG. 1 is a schematic diagram of a server enclosure including a passive thermal dissipation heat sink device according to an embodiment. [Diagram 31] FIG. 2 is a schematic diagram of an active thermal dissipation heat sink device in an embodiment. [Diagram 32] FIG. 2 is a schematic diagram of a passive thermal dissipation heat sink device in an embodiment. [Diagram 33] FIG. 2 is a schematic diagram of an active thermal dissipation heat sink device in an embodiment. [Diagram 34] FIG. 2 is a schematic diagram of an active thermal dissipation heat sink device in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Figure 1 is a diagram of a portion of the electromagnetic spectrum, including the transmittance of a subset of electromagnetic energy at various wavelengths. Infrared radiation is a type of energy that is invisible to humans, but is sensed as heat or thermal radiation. Figure 1 shows a section of the infrared region, including reflected, or near-field, and far-field infrared.

[0011] As shown in Figure 1, the Earth's atmosphere generally has three atmospheric transparency windows in the infrared range through which energy can freely transmit and pass through the atmosphere to the outside space. The atmospheric transparency windows include the 4-5 μm spectral range, the 8-13 μm spectral range, and the 16-26 μm spectral range. These transparency windows can be exploited to pump heat or energy into the effective heat sink provided by the outside space. This is called radiative cooling. Both nighttime and daytime radiative cooling techniques have been developed with the explicit goal of keeping the Earth's surface below the temperature of the outside air. Daytime radiative cooling is technically possible, but highly reflective substrates are used to prevent absorption of the incoming solar radiation.

[0012] One of the primary advantages of employing radiative cooling techniques in computer servers is that the servers are already shielded from incident solar radiation, and the primary heat source driving the radiative effect comes from the kinetic transfer of thermal energy from the server components. The server components themselves are constructed from a combination of plastics, metals, and semiconductors. Each of these materials has a different transmittance of corresponding wavelengths, but careful consideration of the placement of infrared windows within the server housing, as well as the materials used for the data center construction and enclosure itself, can allow much of the energy in these ranges to pass while minimizing attenuation.

[0013] Various embodiments of the proposed passive heat sink device allow for the integration of multiple radiative cooling technologies into a single device. A passive heat sink device involves engineering the surface properties of a bulk heat sink material and its components to provide a heat sink device that comprises a thermal metasurface framework combined with a specific geometry that results in a sky-facing surface area. By simultaneously controlling the spectral range radiated by the bulk heat sink material, the shape and scale of the surface patterning, and the topology of the passive heat sink device, it is possible to tune the spatial coherence, temporal coherence, directionality, and focal position of the radiation emitted by the device.

[0014] Employing metamaterial design techniques allows precise control over the density, absorption, transmittance, and reflectance properties of bulk heat sink materials. These features, combined with careful design of topology and narrowband emissivity in the atmospheric transparency window, enable dissipative heat sink devices to become the basis of an entirely new class of thermal management solutions.

[0015] 2 shows a perspective view of a passive heat sink device 100 configured to couple to a heat source in one embodiment. The device 100 includes a radiator 180 having a concave parabolic fin or emitter 102, a focusing rod 108, and a cold plate 106. The central focal plane of the concave parabolic fin or emitter 102 is centered and coupled to the upper surface of the cold plate 106 such that the concave parabolic fin or emitter 102 faces upward toward the focusing rod 108. The focusing rod 108 is spaced apart from the concave parabolic fin or emitter 102. Its shape may be like a half pipe with a lower convex surface 119 and an upper planar side or emitter surface 120. The lower surface of the cold plate 106 is configured to be attached to a heat source.

[0016] In one embodiment, the focusing rod 108 is attached to support bars 110 and 112 that protrude from either end of the upper concave surface 103 of the central focal plane of the concave parabolic fin 102. In this manner, the focusing rod 108 is spaced apart from the upper surface 103 of the parabolic fin or emitter 102 and oriented widthwise along the central focal plane of the parabolic fin 102. However, it should be appreciated that other structural features than a pair of support bars 110 and 112 may be used to space the focusing rod 108 from the upper concave surface of the parabolic fin 103 or emitter 102. An opposing magnetic field may be used to suspend the focusing rod relative to the support bars, or the optical coupling itself may serve to balance or suspend the focusing rod.

[0017] FIG. 3 shows a schematic diagram of a passive heat sink device 100. As shown, the concentrating rod 108 comprises a lower portion 116 having a lower convex surface 119 and an upper portion 118 having an upper planar or emitter surface 120. In one embodiment, the lower convex surface 119 of the lower portion 116 provides a focal point for concentrating the thermal energy or coherent infrared radiation emitted from the concave parabolic fin or emitter 102, as shown in FIG. 3. The upper planar surface of the emitter surface 120 defines the top of the upper portion 118 of the concentrating rod 108 and comprises a surface, such as a thermal metasurface, that collimates, focuses, and conditions the concentrated thermal radiation 12 away from the heat source and toward an upper optical coupling to a fiber optic bundle or line-of-sight optics for routing. The concentrated thermal radiation 12 may also exit through a window, lens or absorber 105 in a casing 101 surrounding the passive dissipation heat sink device 100. For example, the casing 101 may be a server casing surrounding the passive dissipation heat sink device 100 and providing a heat source for a computer server. If the element 105 is a window or lens, the concentrated thermal radiation 12 leaves the casing, and if the element 105 is an absorber, the concentrated thermal radiation 12 is stored in a thermophotovoltaic, photovoltaic or thermoelectric generator element coupled to an electrical energy storage system such as a battery or capacitor, and the thermal energy carried by the radiation is converted directly into electrical energy by the photovoltaic or thermoelectric generator element and stored for subsequent use. Alternatively, the thermal energy may be stored directly in the server casing 101.

[0018] 4 shows a schematic diagram of another embodiment of a passive dissipation heat sink device 200. The passive dissipation heat sink device 200 includes a radiator 280. In FIG. 4, a concentrating rod 208 is configured to connect a metal "light pipe" or fiber optic cable that transfers the concentrated thermal infrared energy or emitted thermal radiation 12 from the heat source and device 200 to the outside of the casing 201. A lower portion 216 of the focusing rod 208 having a lower convex surface 219 absorbs the coherent infrared radiation 10 from the concave surface 203 of the concave parabolic fin or emitter 202, and an upper portion 218 includes an upper planar surface 220 that defines the top of the upper portion 218 and has a surface, such as a thermal metasurface, that converts the absorbed energy 10 into a wavelength of focused thermal radiation 12, such as focused infrared thermal radiation, that can be reliably transmitted through a pipe or optical fiber. Once the focused radiation 12 is directed towards the boundary between the casing 201 and the environment outside the casing 201, optical dispersion techniques can be used to uniformly emit the focused radiation 12 from the exit point shown.

[0019] In the embodiments shown in Figures 2, 3, and 4, the directionality in space can be controlled by thermal metasurfaces on the top planar surface or on the emitter faces (120, 220) of the focusing rods (108, 208). Thermal metasurfaces are surfaces of any material functionalized to support integrated light control through the addition of subwavelength surface features. These features can be geometric in nature and can be controlled by etching, lithography, or related patterning techniques employed on the substrate. Alternatively, the thermal metasurface can be added as nano / micro particle dopants embedded in a bulk material matrix. The surface of the radiating fin can be tuned to emit spatially and temporally coherent thermal radiation as a super-Planckian blackbody (exceeding the blackbody limit of radiative heat transfer). The emitter surface features can be tuned to narrowband emissivity in the optical near / mid / far / infrared atmospheric windows.

[0020] As described, the thermal metasurface may be a set of geometries lithographically printed on the top planar or emitter surface (120, 220). For example, lithography can be used to form the geometries in a layer of dielectric material, such as plastic, exposing a metal material underneath. Alternatively, the set of geometries can be cut out of the metal material and then back-embedded with a dielectric material, such as plastic. Alternatively, the properties of the thermal metasurface are determined by the geometry of symmetric nanopillars assembled from the doped substrate. The nanopillars distort into two ellipses, oriented approximately 90 degrees apart, on the alternating surface as the diameter and minor axis vary with δ and the dopant concentration varies with k. These two parameters allow tuning of the thermal radiation efficiency Qr and the "losses" associated with non-radiative recombination Ql, resulting in a radiation Q-factor of:

number

number

[0021] FIG. 5 shows an example diagram of a thermal metasurface configured on the upper plane of the emitter face of a focusing rod, FIG. 5(a), and an example diagram of a thermal metasurface configured on the upper plane of the emitter face of a focusing rod, FIG. 5(a) and FIG. 5(b). As shown, two example alternating ellipses are shown in FIG. 5(a) and FIG. 5(b). Each diagram has alternating lines and perturbations in the angle at which each ellipse is oriented along the x-axis.

[0022] When the dopant concentration and angular orientation are simultaneously perturbed, the thermal metasurface framework allows arbitrary control of the optical properties of the thermal radiation emitted from the surface. In the case of the parabolic fins, the temporal coherence is enhanced to fully tolerate the parabolic bending of the bulk material resulting in focusing. The spatial coherence in this case is controlled by the parabolic nature of the fins. Similarly for the emitter surface, the spatial coherence of the thermal radiation is enhanced to allow collimation of the thermal radiation tailored for narrowband infrared emission in two atmospheric windows of the Earth. When the parabolic fins are super-Planckian emitters (exceeding the limit of radiative heat transfer), the focusing rods act as optical couplings and lenses to facilitate the transfer of the radiation to the optical fiber bundle. Optical routing is then used to direct the propagating thermal photons to a specific point in the sky. If the light is highly temporally and spatially coherent, the radiation can be focused into an energy recovery device. When radiation is emitted only from a narrowband atmospheric window and focused onto the lower lens of the concentrating rod, the parabolic fins act as a heat pump to dump the radiant thermal energy of the concentrating rod by using the apparent low temperature of the concentrating rod as a heat sink (viewing the concentrating rod as a cold path toward equilibrium with the spatial background rather than the local environment).

[0023] In the embodiments shown in Figures 2, 3 and 4, it is important that the upper planar surface or emitter surface (108, 208) of the focusing rod (108, 208) faces the sky. In the embodiment of Figure 3, the upper planar surface of the focusing rod 208 is indirectly exposed through an optically free path via a series of mirrors and lenses. In the embodiment of Figure 4, the upper planar surface of the focusing rod 208 is connected to an optical cable 222, the opposite end of which is directly exposed to the sky-facing environment. In both Figures 3 and 4, the parabolic fins may be stacked along a plane of high thermal conductivity, such as a vapor chamber or anisotropic material with the plane of highest thermal conductivity aligned perpendicular to the cold plate. Such an embodiment is described below.

[0024] FIG. 6 shows a schematic diagram of a passive heat sink device 300 in another embodiment. The heat sink device 300 includes a radiator 380. As shown, the focusing rods of the radiators (180, 280) in FIGS. 2, 3 and 4 are replaced with thin wires 308 whose diameters are limited with sufficient precision to ensure that the concave parabolic fin or emitter 302 remains focused. The device 300 also includes a one-way mirror 326 and a coating 324 on the surface of the parabolic fin 302, including the upper concave surface 303. Coherent infrared radiation 10 is emitted from the parabolic fin 302 and concentrated by the one-way mirror 326 onto the wire 308. A portion 14 of the concentrated radiation is emitted from the wire 308 and returned to the parabolic fin 302, and the coating 324 directs the portion 14 of the concentrated radiation back out of the casing 301. Another portion 16 of the concentrated radiation is optically emitted from wire 308 and reflected out of the casing by one-way mirror 326. The remaining portion 12 of the concentrated radiation is emitted out of the casing from wire 308. If wire 308 is placed in a vacuum and maintained by a chamber that is transparent to the incident radiation but reflects visible radiation, the concentrated radiation heats wire 308 and effectively emits blackbody radiation into the visible range, allowing for an efficient upshift of the concentrated narrowband infrared light to visible wavelength light.

[0025] 6, the spatial and temporal coherence of the thermal radiation from the parabolic fin or emitter 302 is controlled via nano / micro particle doping 324 on the surface 303. The temporal and spatial coherence of the fin surface 303 allows for the emitted radiation to be directed and focused to any focal point or series of points along the focusing rod 308. In this case, the focusing rod is replaced by a thin wire, limited only by the achievable coherence level of the fin and the precision of the parabolic focus along the face of the wire.

[0026] In the passive dissipation heat sink embodiment in Figures 2-3, 4 and 6, the concentrating rods (108, 208) and wires 308 are thermally isolated from the cold plate (106, 206, 306) attached to the heat source. In the passive dissipation heat sink embodiment, the cold plates (106, 206, 305) have common characteristics, including high thermal conductivity, high heat capacity, high melting point, and a different maximum phonon frequency at the top of the cold plate versus the bottom of the cold plate. The characteristics of high thermal conductivity, high heat capacity, and high melting point can be achieved with metals such as copper and aluminum, with copper having a maximum heat capacity of 300 W / m·K. However, exemplary materials and processes for the cold plate to maximize the difference in maximum photon frequency between the top and bottom of the cold plate (106, 206, 306) at the desired temperature range of 25-100 degrees to achieve the desired effect include sintered-based ceramics, multi-material alloys, and physical vapor deposition techniques.

[0027] FIG. 7 shows a perspective view of a passive heat sink 400 with a radiator 480 with stacked interacting fins in one embodiment. In this embodiment, the radiator 480 includes multiple stacked interacting concave parabolic fins 402a, 402b, and 402c. The interacting parabolic fins (402a, 402b, 402c) are stacked such that the focal plane of each fin focuses the coherent thermal radiation to the fin directly above it. This design can utilize surface patterning such as split ring resonators (SRRs) to achieve tuned absorption or frequency-doubling effects that depend on the placement of a particular fin relative to the fins above and below it. Because the thermal radiation is focused to the fin above that particular fin, the radiation from the SRR array defined on the fin must be at a frequency that tunes the adjacent fin above it to absorb it. Frequency doubling allows the radiation emitted from the subsequent SRR array to transfer the stored energy more efficiently.

[0028] The device 400 further includes a cold plate 406 and a focusing rod 408. The focal planes of each of the concave parabolic fins or emitters (402a, 402b, 402c) are located at the center of the cold plate 406, with a first parabolic fin bonded to the upper surface of the cold plate 406 and the concave surfaces of the parabolic fins or emitters (402a, 402b, 402c) facing upwards towards the focusing rod 408. The focusing rod 408 is spaced apart from the concave parabolic fins or emitters 402 and may be shaped like a half-pipe having a convex lower surface 419 and an upper planar surface 420. The lower surface of the cold plate 406 is configured to be attached to a heat source.

[0029] In one embodiment, the focusing rod 408 is attached to a pair of support bars 410, 412 that protrude from either end of the central focal plane of the concave parabolic fins (402a, 402b, 402c). However, it should be understood that other structural features than the pair of support bars 410 and 412 can be used to space the focusing rod 408 from the parabolic fins or the upper concave surface of the emitter 402.

[0030] FIG. 8 illustrates a perspective view of a passive dissipation heat sink 500 having a radiator 580 with stacked non-interacting fins in one embodiment. In this embodiment, the radiator 580 includes multiple stacked non-interacting concave parabolic fins 502. In the embodiment of FIG. 8, the focal point of each parabolic fin 502 controls the spatial coherence of the light, and the temporal coherence is controlled via surface patterning or nano / micro particle doping (e.g., thermal metasurfaces), allowing the emitted radiation to be focused towards any point or series of points along the focusing rod 508. However, in other embodiments of the passive dissipation heat sink, the role of the concentrator along with the parabolic fins may also change.

[0031] 9 shows a perspective view of a passive heat sink 600 with a radiator 680, according to one embodiment. Instead of concentrating radiation along a focal plane of parabolic fins 602 in the radiator 680, the rods 608 of the radiator 680 act as emitters. In particular, the emitter rods 602 are thermally coupled to a heat source 630 at a high thermal conductivity contact point, such as a heat pipe 630, or a heat pipe 632 or a material with anisotropic heat transfer properties, and the parabolic fins 602 are thermally coupled to a cold plate 606 via wires 634.

[0032] The emitter rod 608 does not require surface patterning or etching to achieve coherence. The parabolic fins 602 are coated with an infrared reflective material 624 and are used to collimate the radiation 10 emitted from the emitter rod 608 on the outside of the casing 601. The main radiation source in the embodiment of FIG. 9 is never concentrated. Its highest temperature is the highest temperature of the heat source 630 attached to the cold plate 606. All heat pumped into the cold plate 606 is transferred to the emitter rod 602 via the heat pipes 632. By making the lower half of the emitter rod 608 have a nearly uniform emissivity, for example, the parabolic fins 602 act as a perfect blackbody radiator in the spectral range where they have maximum reflectivity, and the infrared radiation 10 emitted from the emitter rod 608 is directed via the orientation of the fins 602 to a focal point centered on the emitter rod 608.

[0033] 10 shows a schematic diagram of a standard liquid cooling system 700a as an example of the prior art. The cold plate 706a of any liquid cooling system serves to provide a high rate of thermal energy transfer to the system's working fluid, typically liquid water (or a liquid water / glycol mixture), as it flows through the water block 720a from a cold reservoir at the liquid inlet 731a to the liquid outlet 733a. The cold plate 706a provides a fin-based mechanism 735a that directs the flow through the water block 729a, increasing the flow rate over a high surface area and maximizing the transfer of conductive energy from a heat source 730a located on the opposite side of the cold plate 706 to the fluid.

[0034] FIG. 11 illustrates a schematic diagram of a passive dissipation heat sink 700b with a water block radiator 780b in one embodiment. The passive dissipation heat sink 700b is a near-field integrated cold plate that enhances standard water block systems to take advantage of both near-field and far-field thermal radiation or emission effects. Although FIG. 11 illustrates the radiator as a water block radiator 780b, it should be understood that the radiator may be any suitable type of radiator, including radiators 180, 280, 380, 480, 580, or 680 previously described, and may be mounted on top of the cold plate to maximize exposure to the working fluid of the water block.

[0035] The cold plate 706b comprises a ceramic-based material and is coupled to the heat source 730b by a thermal interface material or compound 782b. The cold plate 706b and the material of the thermal interface material 782b enable a new vector of energy transfer via radiation to the working fluid, allowing for faster transfer of heat from the heat source 730b than is achievable with standard materials and configurations. The exemplary working fluid in FIG. 11 is water passing through a water block.

[0036] Thermal energy is transferred from the heat source 730b to the thermal compound 782b, which is tailored by material selection, grain size, grain structure shape, and orientation to be a super-Planckian emitter in the wavelength region best absorbed by the selected cold plate material (ceramic), such that the thermal energy is split by the thermal compound into radiative and kinetic components and absorbed by the cold plate faster than possible using only kinetic transfer of thermal energy. In particular, the thermal compound 782b is configured to convert a portion of the first phononic thermal energy (lattice phonons, kinetic collision energy, or kinetic component) from the heat source into first photonic near-field thermal radiation and first photonic far-field thermal radiation (radiative component), and is configured to simultaneously maximally transfer the first photonic near-field thermal radiation and the first photonic far-field thermal radiation to the cold plate 706b as the remainder of the first phononic thermal energy. The thermal compound 782b heats the cold plate 706b faster (eg, more energy is transferred to the cold plate photons in less time).

[0037] The cold plate 706b includes a bulk material that has a higher cooling power relative to the limit where the motional transfer of heat across the interface is maximized. In other words, the bulk material of the cold plate 706b couples the first photonic near-field thermal radiation, the first photonic far-field thermal radiation, and the remainder of the first phononic thermal energy into a second phononic energy and provides the second phononic thermal energy to the radiator 780b. The heat is transferred to the working fluid of the system. In FIG. 11, the exemplary working fluid is liquid water (or a liquid water / glycol mixture), which may or may not be enhanced to absorb the primary frequency band that the ceramic of the cold plate or the radiator is tuned to emit or absorb relative to the thermal compound. The water flows from the cold reservoir at the liquid inlet 731b to the liquid outlet 733b through the water block 729b and across the radiator 780b attached to the fluid-facing surface of the upper part of the cold plate. The material or material structure of the upper fluid-facing portion of the cold plate (e.g., radiator) can be further dynamically modified to enhance the transfer of both kinetic and radiative thermal energy into the working fluid, depending on the fluid properties (e.g., flow rate, temperature, chemistry). In this paradigm, the working fluid is heated in two ways: kinetic (phonon-mediated) transfer of thermal energy due to the heating of the cold plate, and radiative (photon-mediated) transfer of thermal energy. Radiative thermal energy is released by heating of the cold plate itself, or is released by the thermal compound and / or heat source below and transferred through the cold plate to the working fluid.

[0038] Furthermore, this paradigm allows for two new mechanisms of radiative transfer of energy. First, the heated cold plate can be optimized to maximally emit and transfer thermal radiation in the zone of maximum absorption by the working fluid, while the bottom of the cold plate is tuned to maximally absorb radiation emitted by the thermal interface material. This effect can be further enhanced by optimizing the radiator topology on the fluid contact side to increase the surface contact area of ​​the working fluid for a desired flow rate. Second, the cold plate can be designed to be transparent in various bands of the electromagnetic spectrum, allowing radiation emitted from the thermal compound and / or heat source to be directly delivered into the working fluid or deposited in the bulk material of the cold block. In some embodiments, at least one thermoelectric cooler, or other solid cooling element, is integrated into the bottom of the cold plate, such that the cold side of the solid cooling element faces the heat source and the hot side of the solid cooling element faces the bottom of the radiator or the cold plate surface in contact with the working fluid.

[0039] Figure 12 is a schematic diagram of another embodiment of a passive heat sink 800 coupled to a heat source 830. In particular, Figure 12 illustrates a super-Planckian passive heat sink 800 that includes a radiator 880, a cold plate 806, and a thermal interface material or thermal compound 882. The radiator 880 includes a distributed Bragg reflector (DBR), a woodpile photonic crystal 881, and a blackbody pump layer 884 or a powered coherent light source 884, such as a diode laser, and the cold plate 806 includes a reflector 885 and a bulk material 883. It should be understood that the thermal compound 882 and cold plate 806 operate similarly to the thermal compound 782b and cold plate 780b described above, and that the radiator 880 is an exemplary radiator and may be any of the radiators 180, 280, 380, 480, 580, 680, and 780b described above.

[0040] In the near field, super-Planckian thermal radiation is achieved through a thermal interface material 882. The thermal interface material 882 thermally couples the heat source 830 to the bulk material 883 of the cold plate 806, and includes a thermal compound material configured to control and enhance the effervescent surface waves thermally excited at the heat source 830. The thermal interface material 882 includes a dielectric and electrically insulating thin film substrate capable of super-absorbance and super-Planckian radiation. The thermal interface material 882 is configured to drive the thermal energy of the surface waves at the heat source 830 to propagate into the thermal compound or thermal interface material via near field interactions along nano / micro metallic particles loaded in the dielectric substrate of the thermal interface material. Near-field thermal radiation is driven to strongly interact with material along the cold plate surface, simultaneously maximizing the motional transfer of heat from the heat source 830 to the cold plate 806 (via conventional surface vessel minimization and gap filling) and the near-field thermal radiative transfer to the cold plate 806 via surface waves.

[0041] In the far field, super-Planckian thermal emission may be achieved by spatial and temporal coherence via three-dimensional metallic photonic crystal lattice structures, as described below, and by optical band gap mixing.

[0042] FIG. 13 shows a perspective view of radiator 880, and FIG. 14 shows a side view of FIG. 13 including radiator 880 with woodpile photonic crystal 881 and DBR 882. Some embodiments including DBR 882 include where DBR 882 is a top layer or coating deposited or attached on top of photonic crystal 881 to act as a narrow passband filter, above the top unit cell layer L=N, that reflects wavelengths other than the optical band edge or narrow passband near the effective plasma cutoff frequency caused by the tailored diamond lattice symmetry structure in photonic crystal 881. For example, DBR 882 can be composed of thin film stacked layers of alternating materials such as silicon and silicon oxide, transmitting only the sharp narrow band super-Planckian thermal radiation emitted by each layer L to the environment, and maximally reflecting all other frequency bands. Additionally, in another embodiment, the top layer of the photonic crystal can be modified to further increase directionality and constrain the angle of the emitted thermal photons to be spatially and temporally coherent.

[0043] The woodpile photonic crystal 881 of the radiator 880 comprises any number of individual and alternating stacked layers of refractory metal material "plates" or "beams" 887 forming a "woodpile" configuration. Four layers of n stacked "plates" or "beams" 887 comprise unit cells 889, each of which defines the photonic crystal 881 to have diamond lattice symmetry (dashed lines in FIG. 14). Each "plate" or "beam" structure 887 has a height H (z dimension), a width W (x dimension of the top layer in the figure below), and an arbitrary length L (L in the y dimension of the top layer). y , L in the x-dimension of the second-highest layer x), with a distance A between adjacent beams. When four layers of beams are stacked, the beams in each layer are rotated by Φ=90 degrees relative to the next layer. Let the peak of the function sin(x+θ) represent the center position of each plate in the top layer, and the peak of the function sin(y+θ) represent θ=0 for the top two layers. The last two layers are set at θ=π relative to the first two layers, which uniformly shifts the phase of the plate positions. Four layers of beams (H, W, L) in a lattice unit cell layer L are x , L y The parameters defining A) and B) are constant but vary as multiple unit cell layers are stacked up to N times.

[0044] The final layer of the top PC unit cell layer (L=N) serves to maximize the spatial coherence of the emitted thermal radiation. The parameters of the length of the beam, L, and the number of plates, n, are split into two components. For L, the components are L and N, respectively. x , and L y The number of plates in each dimension is n x , and n y It is.

[0045] Each beam can be of any length L, so long as the lattice spacing or inter-beam spacing (A) and the ratio of beam height (H) and beam width (W) are maintained, allowing the photonic crystal 881 to retain its super-Planckian passive thermal radiation properties (i.e., violating the blackbody radiation law in spectral intensity, coherence, angle, and directionality). Maintaining the ratio of spacing A, height H, and width W means adjusting, scaling, spacing, and orienting spacing A, height H, and width W relatively to produce the narrowband radiation required for passive radiative cooling and emit more blackbody radiative power per unit area than predicted by the Planck radiation law. For example, the height H of each beam 887 can be one-half (½) of the beam-to-beam spacing and the width W can be one-third (⅓) of the beam-to-beam spacing, meaning that the width W of each beam 887 is less than the height H of each beam 887 and the beam-to-beam spacing A is greater than the width W and greater than the height H. Meanwhile, the length L of each beam 887 can be any dimension depending on the application.

[0046] The refractory material defining the woodpile photonic crystal 881 has a surface roughness on the order of tens of nanometers sufficient to support excited surface plasmon resonances. The super-Planckian passive heat sink 800 further enhances emission, emitting or transmitting along specific narrow bands to define the Earth's atmospheric windows in the 4-5 μm, 8-13 μm, and 16-26 μm wavelength spectral ranges, thereby allowing the bulk device to exhibit or transmit super-Planckian near-field thermal radiation and super-Planckian far-field thermal radiation in the bands associated with the atmospheric windows while simultaneously acting as a highly reflective radiative cooler in all other bands. For example, the refractory material in each "beam" includes tungsten. Pure tungsten has a unique crystal structure, but the photonic crystal "beams" are fabricated in such a way as to create new crystal structures of tungsten.

[0047] Planck's radiation law, which is the spectral radiance of an object (B) as a function of wavelength (λ) and temperature (T), is written as Equation 3:

number

number

number

[0048] Usually, the emissivity of an object is a surface property that characterizes the blackbody radiation in a particular wavelength range. For an ideal blackbody, the power radiated from the object at a certain temperature can be completely described by B(λ,T) for each wavelength. Only by integrating over all frequencies (or wavelengths), all angles, and the entire surface, do we arrive at the total power radiated. Thus, as an object approaches the ideal blackbody radiation limit, its emissivity approaches 1.

[0049] This normalization has historically served as a justification, from concepts of statistical mechanics, for ignoring the radiative component of heat transfer when designing cooling solutions. 2 At modest package temperatures (<100 °C) found in modern HPC processors (currently operating at <300 W), the Stefan-Boltzmann law dictates that the power emitted in the form of radiation will be less than 2 W, even assuming perfect blackbody emissivity.

[0050] However, the Stefan-Boltzmann law does not apply to objects at wavelength and subwavelength scales, or objects whose surfaces contain nanostructures. By maximizing the number of thermal photons emitted from the surface of the radiator 880 per unit time along with temporal and spatial coherence, the super-Planckian passive heat sink 800 can pump hundreds of watts of power into the far-field infrared band from the same surface area, while the inherent focusing nature of the coherent radiation enables novel energy harvesting schemes. In fact, super-Planckian thermal emission can occur at any wavelength if the object radiates more power than predicted by B(λ,T). In practice, such super-Planckian thermal emission is achieved by making one or more dimensions of the emitting object smaller than the thermal wavelength of the emitted light, by designing materials to expose surface features below the thermal wavelength on the surface of a larger emitting object, or by designing features that enhance the temporal and spatial coherence of the thermal photons.

[0051] As mentioned above, the Plank radiation law B(λ,T) gives the spectral emission power per unit area, per unit solid angle, and per unit frequency. It includes the assumption that the emitter has uniform properties in all spatial dimensions, as well as the assumption that thermal radiation follows the Lambertian emission law, which is a restatement of the assumption that blackbody radiation is incoherent in both space and time.

[0052] Thus, super-Planckian near-field thermal emission and super-Planckian far-field thermal emission can result from spatially modulating the directionality of emitted thermal photons (e.g., violating the Lambertian assumption) or from increasing the rate of electronic processes that lead to the excitation of localized surface plasmons. In the latter case, constraints on localization are imposed by the diamond symmetry of the woodpile topology of the photonic crystal 991, as well as the micro- and nanostructures that define its surface. The photonic crystal 881 is "tunable" and has seven free parameters, including the beam 887 of spacing A, the beam 887 of width W, the beam 887 of height H, the DBR 882 of thickness T, the power supplied to the heat source 830, the material of the photonic crystal 881, and the material (e.g., air, polymer) located between the gaps of the photonic crystal 881.

[0053] Below the photonic crystal 881 (L=0) is placed an ideal blackbody pump 884 of radiator 880 (i.e., blackbody pump material), such as a layer of densely aligned carbon nanotubes (CNTs) or nanostructured tungsten, which acts as an ideal blackbody emitter with ideal thermal conductivity. The blackbody pump 884 is configured to maximize both phonon-mediated and photon-mediated heat transfer to the photonic crystal 881, and thermally connects the photonic crystal 881 to the cold plate 806. Alternatively, the blackbody pump can be replaced by a coherent light source, such as an optical signal generator that actively pumps coherent laser light into the base of the super-Planckian photonic crystal, or incorporates a frequency pumping mechanism into the base of the super-Planckian photonic crystal, which enhances the temporal coherence of the emitted super-Planckian thermal radiation.

[0054] In the simplest embodiment, only a single unit cell layer (i.e., L=N=1) is needed to emit super-Planckian thermal radiation in a single narrowband region in any atmospheric window. In other embodiments, multiple unit cell layers L=1,2,3...N can be stacked, with each unit cell layer varying the lattice parameters (H, W, L) relative to the subsequent unit cell layer below it (i.e., L-1). x , L y , and A) are different. Thus, the radiator 880 of the super-Planckian passive heat sink 800 emits super-Planckian narrowband thermal radiation in one or more atmospheric windows of the Earth. The radiator 880 transfers heat from the cold plate 806 to the photonic crystal 881, which pumps the heat to outside space through one or more frequency bands that define the atmospheric windows of the Earth.

[0055] The cold plate 806 serves to thermally connect the heat source 830 to the radiator 880 and provide a thermal reservoir for heat deposited from the heat source 830. The cold plate 806 includes a reflector 885 deposited on a bulk material 883. The reflector 885 is a thin metallic or polished ceramic layer of material that acts as an ideal reflector over all relevant wavelength bands of atmospheric infrared light, solar radiation, as well as blackbody radiation and narrowband radiation emitted by the radiator 880. The reflector 885 operates such that any thermal radiation from the environment or the radiator 880 is reflected rather than absorbed by the bulk material 883 of the cold plate 806.

[0056] The bulk material 883 is capable of maximum absorption over the full range of wavelengths of interest for the following heat source 830 and thermal compound, and has high thermal conductivity, high heat capacity, and high electrical resistivity as described above in the previous embodiment. Exemplary materials include silicon carbide (SiC), man-made ceramics, and other materials with similar properties.

[0057] The thermal interface material 882 is composed of a bulk material 883 and a material that has a high thermal emissivity relative to the temperature of the heat source 830. The thermal interface material or thermal compound includes particles or structures with high thermal conductivity, high emissivity, and high spatial anisotropy in one dimension, meaning that its width and diameter are much larger (e.g., microns) than its height (e.g., on the order of nanometers). The particles or structures may or may not be made of metal or ceramic. Part of the thermal compound may be composed of carbon nanotubes of a specific size to match the absorption characteristics of the bulk material of the cold plate and / or the working fluid and its components. It should be understood that an exemplary working fluid may include an aqueous liquid if the radiator is a water block, but may also be gaseous particles that make up the environment of the external space. The constituent particles and structures containing the thermal compound are enhanced to emit super-Planckian thermal radiation into both the near and far regions of the electromagnetic field surrounding the incorporated particles and structures, through the substrate (e.g., polymer, epoxy, or dielectric fluid) in which they are loaded, and into the surroundings, and to maximize the thermal radiation emitted by the constituent particles and structures is deposited into or through the material of the cold plate, or into the working fluid of the water block in the case of a direct liquid cooling based system.

[0058] The principle in manufacturing an ideal cold plate for attachment to a thermally dissipating heat sink is to maximize the penetration depth (or skin depth) of the radiation emitted from the thermal interface material into the bulk material of the cold plate. Skin depth is defined as the distance over which the amplitude of the incident electromagnetic wave is reduced by 1 / e for any material,

number

[0059] The super-Planckia passive heat sink 800 achieves super-Planckian thermal radiation in both the near and far infrared regions, incorporates super-Planckian thermal radiation into both the conceptual energy input and output channels of the device 800, broadband non-equilibrium heat pumping occurs in the bulk material 883, both broadband heat pumping into the electromagnetic field and narrowband non-equilibrium heat pumping occurs at the output, and the temperature of the bulk material 883 is driven below that of the local environment and atmosphere. The equilibrium state of the bulk material 883 reaches the average temperature of the cosmic background radiation of the local universe.

[0060] In yet another embodiment, the heat dissipating heat sink may be an actively cooled radiative heat sink that integrates some features of a passive heat dissipating heat sink and adds an additional element that requires dynamic adjustment of the input power based on a sensor feedback mechanism. The sensor feedback comes from an array of temperature sensors integrated on the surface of the cold plate and / or sensors interacting with infrared (1 μm-30 μm), terahertz (30 μm-3 mm), microwave (3 mm-1 m) or radio (>1 m) radiation, allowing spatial and temporal awareness machine learning models to recognize any high-resolution spatial information about the temperature distribution on the surface of the heat source, as well as any high-resolution spatial and temporal dynamics occurring within the heat source. When the heat source is a processor or CMOS-based device, the dynamics occur in the range of the clock speeds used to drive the logic operations on the chip. The sensors in these cases are arrays of metallic loops embedded in a dielectric substrate layer within the bulk material of the cold plate, or directly on the surface of a highly thermally conductive insulating substrate at the cold plate surface, sized to be tuned to the frequency range of interest (e.g., the 1-10 GHz range for HPC processors). When these frequency logging sensors are distributed as an array on the cold plate surface, they act as spatial markers that indicate the location of the emerging radiation dynamics.

[0061] A well-trained machine learning model is then used to perceive both the spatial and temporal dynamics of the radiation emanating from the computer chip and decode these signals into raw instructions or application-level performance information. Both active and passive embodiments of the thermal dissipation heat sink can be optimized to utilize a combination of optical, thermal, infrared, THz, GHz, and MHz frequency sensors described above to sense the microprocessor dynamics and to control various properties of the heat sink (e.g., near-field transmission from the heat source, frequency and polarization of the far-field thermal radiation from the radiator, bias voltage applied across the ELC elements) in real time and in a responsive manner. Sensors that detect local atmospheric conditions (e.g., humidity) can also be used with machine learning models to dynamically adapt the frequency of the emitting ELC elements or radiators so that the emitted wavelength is tuned to not interact with, or conversely to interact strongly with, the various constituent chemicals (e.g., water vapor) that define the local atmosphere. Regardless of the particular sensor feedback mechanism, these additional elements act symbiotically to pump heat from the heat source into the electromagnetic spectrum at a higher diffusivity than would be possible using only a passive bulk material or alloy.

[0062] FIG. 15 shows a schematic diagram of an active dissipation heat sink device 900 in an embodiment. In particular, the active dissipation heat sink device 900 includes a gap adjustment active cold plate 940, a gap actuator controller 942, and a near-field radiative heat transfer (NF-RHT) and optimizer 944. The gap actuator controller 942 and the NF-RHT optimizer 944 are configured to actively cool the heat source 930 by actively controlling the gap spacing as a function of temperature or thermal expansion of the material. The gap actuator controller 942 varies the distance between the gap actuator controller materials (gap adjustment) to achieve near-field thermal radiation beyond the blackbody limit, improving the effective thermal conductivity and heat flux in a real-time responsive and controllable manner. In some embodiments, alternating layers of bulk cold plate material, gap filling dielectric, and gap adjustment actuator may be stacked to further enhance near-field radiative transfer.

[0063] When heat is transferred through a bulk material, the material expands as the temperature of the lattice increases. The rate at which the material expands is a function of pressure, volume, and temperature. When pressure is constant, the rate of expansion (α) is calculated by Equation 6 as follows:

number

number

[0064] The thermal conductivity of bulk materials is generally the limiting factor for rapid heat transfer from a hot spot on a device, such as a computer processing unit (CPU) or graphics processing unit (GPU), to the environment. In a dissipative heat sink, a cold reservoir is provided from outside space, which requires that all of the heat in the bulk material be converted to far-infrared radiation, with wavelengths that fall within all of Earth's infrared and optical atmospheric windows.

[0065] One of the few possible ways to improve the thermal conductivity of bulk materials is to focus on increasing the effective thermal conductivity of the bulk material by adding small sub-wavelength vacuum gap spacing between layers. The conductivity of the solid part of the material is not changed by this technique, but the effective speed at which thermal energy moves through the layers is significantly increased by near-field thermal radiative transfer. For example, by keeping the gap spacing between layers at about 100 nm and the temperature delta between the two layers at about 50 °C K, a device can operate from hot side to cold side with radiative heat flux exceeding 10,000 W / m2.

[0066] The gap adjusted active cold plate 940 includes a first sensor array 946 coupled on one side to the heat source 930 and coupled on the other side to a micro-pillar actuator array 947. The first sensor array 946 measures the temperature at different locations on the heat source 930 and provides that information to the optimizer 944. The gap adjusted active cold plate 940 also includes a second sensor array 948 on the other side coupled to a micro-plate array 949. The second sensor array 948 measures the temperature at different locations on the gap adjusted active cold plate 940 and provides that information to the NF-RHT optimizer 944. A group of four pillar elements of the micro-pillar actuator array 947 is coupled to a single plate element of the micro-plate array 949. Each of the four pillar elements of the array 947 connects four corners of the plate element. This arrangement allows the angle of the plate element relative to the lower surface to be controlled. The volume and temperature of the pillar element material fluctuates and based on the temperature sensed by the first sensor array 946 and the second sensor array 948, the gap actuator controller 942 responds by adjusting the four pillar actuators to maximize the near-field radiative heat flow.

[0067] 16 shows a schematic diagram of an active dissipating heat sink device 1000 in another embodiment. The active dissipating heat sink device 1000 is based on the principle of electroluminescent cooling (ELC). In this embodiment, a single ELC element is referred to as a solid-state emitter (SSE).

[0068] Similar to how solid-state heat pumps such as thermoelectric coolers (TECs) move heat through the kinetic transfer of energy from the cold side to the hot side of the device, ELC-based technologies aim to pump heat using the conversion of thermal energy to light energy in solid-state devices. A simple ELC device is comparable to a highly efficient LED or quantum dot operated with a negative bias voltage. For ELC to occur, the energy of the emitted photons (E out =h f ) is the energy of the charge carriers injected into the junction (E in =qV), and E out >E in The ELC has physical meaning because the additional energy comes from the thermal energy (phonon-mediated thermal energy) of the semiconductor crystal lattice that constitutes the SSE.

[0069] The active heat dissipation heat sink device 1000 includes an active radiator 1050, a sensor array 1046, a grid of SSEs 1049, a bias voltage controller 1043, and an ELC optimizer 1045. The bias voltage controller 1043 and the ELC optimizer 1045 are configured to provide active fine-grained control of the bias voltage as a function of temperature distribution. The controller 1043 provides electrical connections and sensor feedback from the grid of temperature sensors to the optimizer 1045. The sensor array 1046 is on one side of the ELC radiator 1052, and the SSE array 1049 is on the other side of the ELC radiator 1052. The sensor array 1048 is coupled to the heat source 1030 and measures the temperature and / or dynamics of the emitted GHz, THz, or infrared radiation at different locations on the heat source 1030 and provides that information to the optimizer 1045. The bias voltage controller 1043 and ELC optimizer 1045 maintain fine-grained control of the bias voltages applied to the individual heat pump elements defined by the grid of the SSE array 1049. It is also possible to additionally control the frequency of the radiation emitted from the SSE array 1049.

[0070] 17 shows a schematic diagram of an active dissipation heat sink device in yet another embodiment. In particular, the active dissipation heat sink device 1100 includes an active radiator 1150, an active cold plate 1140, a gap actuator controller 1142, a NF-RHT optimizer 1144, a bias voltage controller 1154, and an ELC optimizer 1145. In this embodiment, there are two coupled machine learning models. The near-field model maps the spatial and temporal temperature distribution of the heat source 1130 to a voltage or current signal to the micro-pillar actuator array 1147. The far-field model maps the spatial and temporal temperature distribution of the micro-plate array 1149 to maintain the optimal bias voltage of the ELC themitter for maximum conversion of near-field radiative heat flow to far-field heat flow. Each microplate array element 1149 includes a temperature sensor in contact with the substrate, which acts as an insulated passive heat sink or powering subarray of ELC emitters. The intrinsic losses due to conduction through the microplate array 1149 to the micropillar array 1147 can be further reduced by attaching each actuator 1149 to a magnetic element and constructing the substrate housing the subarray of ELC emitters 1149 from a diamagnetic material so that it is suspended. This constrains the orientation of the device 1100 relative to the Earth's gravitational field, but has the advantage that the device 1100 eliminates all parasitic losses due to conduction, since the gap is kept vacuum or insulating. This is important because the cold side of the device 1100 is presumed to face the sky (or be connected to an optical channel through which radiation may pass with minimal attenuation, such as a fiber optic cable) which acts as the cold side on which near-field radiative heat flux accumulates. The amount of power that can be dissipated increases linearly as the temperature difference between the hot side facing the heat source 1130 (e.g. CPU / GPU) and the cold side facing the sky increases. Additionally, the cold side of the device simultaneously houses an ELC emitter 1149, which becomes more efficient as it approaches cryogenic temperatures.If the emitters can be thermally isolated from the surrounding environment during operation, all of the thermal flux that accumulates in the far field from the near field thermal radiation can be efficiently pumped via electroluminescent cooling. The efficiency of the active thermal dissipation heat sink device 1100 is maximized when the microplate array substrate 1149 is also passively cooled by the radiative cooling effect.

[0071] While the above passive and active heat sink embodiments pump heat from a heat source into the electromagnetic spectrum, more detail is needed on how to move the thermal radiation from the server device to other locations in the data center for energy recovery and / or dissipate the thermal radiation into external space. To remove thermal radiation from an enclosed server with passive and active heat sinks, a facility must be provided for removing the emitted power from the enclosure. In one embodiment, and the embodiment shown in FIG. 3, the enclosure includes a transparent window for the wavelength region in which the heat sink converts its thermal energy for line-of-sight transmission. In another embodiment, and the embodiment shown in FIG. 4, a fiber optic coupling mechanism is provided for routing the radiation into an optical channel embedded within the enclosure. While Figures 3 and 4 depict passive dissipative heat sinks (100, 200) disposed within an enclosure (101, 201), respectively, it should be understood that any of the dissipative heat sink embodiments illustrated in Figures 6-9, 11-12, and 15-17 may be disposed within an enclosure, such as enclosure 101 and enclosure 201, and require thermal radiation to be removed from the enclosure.

[0072] In line-of-sight embodiments, an infrared window may be included in the enclosure above each device with a dissipative heat sink, and / or mirrors and lenses may be added. In both active and passive embodiments, as shown in the enclosed embodiment of Figure 3, the infrared window is transparent to the wavelength range into which the dissipative heat sink converts its kinetic energy.

[0073] FIG. 18 illustrates an embodiment of a diagram of an enclosure 1201 having a thermal dissipative heat sink 1200 that utilizes a series of infrared reflective mirrors to route thermal radiation in a line-of-site configuration. As shown, thermal radiation 10 is concentrated and collimated into thermal radiation 12 that is emitted through infrared window 1203 and reflects off mirrors 1260 and 1262. Although heat sink 1200 is a type of heat sink that utilizes a radiator with parabolic fins and concentrating rods, it should be understood that heat sink 1200 of FIG. 18 may be any of the thermal dissipative heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0074] FIG. 19 shows a diagram of multiple enclosures 1201 with a thermal dissipative heat sink 1200 utilizing a series of infrared reflecting mirrors to route thermal radiation in a line-of-sight configuration in one embodiment. As shown, the enclosures 1201 and optics (1203, 1260, 1262) are stacked in a rack, with additional optics routing the infrared radiation to rack-level reflectors. The collection of all rack-level reflectors is then assembled into collimating lenses for the entire data center, or directed at ceiling tiles with infrared windows directly above each rack. While the heat sink 1200 in FIG. 19 is a type of heat sink utilizing a radiator with parabolic fins and concentrating rods, it should be understood that the heat sink 1200 in FIG. 19 can be any of the thermal dissipative heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0075] Similarly, optical fiber can be an alternative to line-of-sight optical approaches, providing precise control over how routed radiated power can be directed around obstacles, dispersed to sky-facing environments outside the data center, or directed to various focal points for energy harvesting scenarios.

[0076] FIG. 20 shows a schematic diagram of multiple enclosures 1201, each with a thermally dissipative heat sink 1200 coupled to the light channel enclosure in one embodiment. A key feature of the light channel enclosure is a fiber optic coupling 1270 located above, connected to, or directly connected to a focusing rod 1208. The coupler 1270 takes advantage of the fact that the emitted radiation is focused to a specific point. The coupling mechanism must provide a low-loss connection to the element that efficiently focuses or emits the radiation, so that the incoming radiation can be directed into a standard optical fiber with high transmission in the wavelength region that the radiator is tuned to emit. While the heat sink 1200 in FIG. 20 is a type of heat sink that utilizes a radiator with parabolic fins and a focusing rod, it should be understood that the heat sink 1200 in FIG. 20 can be any of the thermally dissipative heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0077] 21 and 22 show perspective views of a server rack 1300 configured to house multiple server casings in one embodiment. Note that for clarity, the multiple server casings are not shown. However, the server rack 1300 shows multiple heat dissipating heat sinks 1200 attached to server boards 1209 and coupled to fiber optic couplings 1270 shown diagrammatically in FIG. 20. The optical couplings 1270 are located above each heat dissipating heat sink 1200. Radiation is directed to fiber optic cables 1211. The accelerators are typically GPUs or ASICs (application specific integrated circuits). In FIG. 21, it is assumed that there are four heat dissipating heat sinks, each operating at about 300W. Although the heat sink 1200 of Figures 21 and 22 is a type of heat sink that utilizes a radiator having parabolic fins and concentrating rods, it should be understood that the heat sink 1200 of Figures 21 and 22 may be any of the dissipative heat sinks illustrated in Figures 6-9, 11-12, and 15-17.

[0078] FIG. 23 is a perspective view of a server rack 1400 configured to house multiple server casings 1201, each with a heat dissipating heat sink attached to each optical coupling, feeding a collective fiber optic bundle or collective light pipe at the rear of the rack, in one embodiment. Note that one server casing is not shown for clarity. The server rack 1400 shows multiple heat dissipating heat sinks 1200 in the missing server casings attached to server boards 1209 and coupled to fiber optic couplings 1270. Radiation is directed in fiber optic cables 1211 into a housing 1213, then vertically through one or more cables that extend toward the ceiling of the space in which the server rack 1400 is located. The housing 1213 collects the fiber bundles exiting each heat dissipating heat sink 1200 into a larger bundle and connects to a pipe 1216. Although the heat sink 1200 of FIG. 23 is a type of heat sink that utilizes a radiator having parabolic fins and concentrating rods, it should be understood that the heat sink 1200 of FIG. 23 may be any of the dissipative heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0079] FIG. 24 shows a perspective view of a distributed radiation server room or data center including multiple server racks 1400 configured to house multiple server casings 1201 in one embodiment. In FIG. 24, the total radiant power from each server rack 1400 deposits thermal radiation into routed light pipes or fiber optic bundles that are routed and attached to collimating lenses on the roof and face the sky. Thermal radiation is distributed through sky-facing infrared windows 1215 (one window above each set of racks 1400) via fiber optic cables or line-of-sight optics and emitted to the outside space. Each window is equipped with a dispersing lens, and the total thermal radiation from each set of racks 1400 is distributed 180 degrees into the sky from a single lens. The use of dispersing lenses allows high intensity infrared radiation to be evenly distributed across the whole sky. Sky-facing heat dissipating datacenter approaches utilize fiber or line-of-sight to achieve sub-ambient temperatures for datacenter devices such as server devices. The thermal metasurface employed in each heat dissipating heat sink is tailored to focus infrared radiation to the rack-local routing system (e.g., cables, or lenses / mirrors) while shifting the wavelength region where the peak radiant power is emitted to the atmospheric transparency window. This requires the emitter to be exposed toward the sky, so that sub-ambient temperatures can be achieved for the local environment. While the heat sink in FIG. 24 is a type of heat sink that utilizes a radiator with parabolic fins and concentrating rods, it should be understood that the heat sink in FIG. 24 can be any of the heat dissipating heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0080] FIG. 25 shows a perspective view of an adaptive light emission server room or data center including multiple server racks 1400 configured to house multiple server casings 1201 in another embodiment, which transmit radiant heat energy through light pipes or fiber optic bundles routed and attached to an adaptive light distribution system. In a variation from FIG. 24, in the embodiment of FIG. 25, assuming that the light emitted from the thermal heat sink is highly coherent, the dispersing lens is replaced with a collimating optic 1415 that can be used to collimate the radiation and direct it to a point in the sky with an area proportional to the area of ​​the aperture. If the collimating optic is replaced with a reflecting tube or telescope aperture with adaptive optics as commonly deployed in automated sun-tracking applications (such as solar), the aperture can follow the opposite path of the sun and maintain a path of no (or reduced) solar irradiance for the thermal radiation to follow. The heat sink of FIG. 25 is a type of heat sink that utilizes a radiator having parabolic fins and a concentrating rod, however, it should be understood that the heat sink of FIG. 25 may be any of the dissipative heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0081] FIG. 26 shows a perspective view of an aggregate radiative server room or data center in another embodiment, including multiple server racks 1400 configured to house multiple server casings, which are configured to route thermal radiation to a focal point in the center of the space via line-of-sight optics, collimating and focusing the radiation to a common point in the sky. In FIG. 26, the aggregate radiant power from each server is focused onto a local heat sink or thermal reservoir 1500 in the data center using line-of-sight optics or fiber optic cables, but does not require explicit surface-to-surface contact between the emitters and the outside space. Instead, the focusing effect enabled by each dissipative heat sink can be used to focus the infrared radiation into a classical dissipation strategy using a heat sink (such as a fan or liquid-cooled radiator) connected to the thermal reservoir of the Earth. In this form of radiative cooling, heat dissipates from each server or rack, focusing the emitted radiation in a geometric distribution onto any absorbing surfaces, which then dissipate the heat into the environment. This format does not allow the server to go below ambient temperature.

[0082] FIG. 27 shows an enlarged cutaway view of an optical coupling 1270 as shown in FIG. 21 and FIG. 22 in one embodiment. The optical coupling 1270 is coupled to the upper planar or emitter surface 1220 of the focusing rod 1208 via optical fibers, in-line reflective light pipes, or line-of-site optical routing. The point of the optical coupling 1270 is to efficiently transmit the thermal radiation emitted by the emitter surface 1220 (with thermal metasurface) of the focusing rod 1208 at relevant infrared and optical wavelengths with low transmission loss. In particular, the optical coupling 1270 transmits the thermal radiation to the environment via the associated cabling or light pipes 1211. After the optical coupling is achieved, the routing of the optical energy along the path is relatively arbitrary, constrained only by the physical layout of the data center or rack, as well as the losses in the cables. Depending on the configuration of both ends of the pipe or fiber bundle, the light emitted at the end may be dispersed into all of the sky or may be directed toward a point in the sky. It should be understood that while the heat sink illustrated in FIG. 27 is a type of heat sink that utilizes a radiator with parabolic fins and a concentrator with a thermal metasurface, the heat sink illustrated in FIG. 27 can be any of the thermal dissipation heat sinks illustrated in FIGS. 6-9, 11-12, and 15-17.

[0083] 28 shows a schematic diagram of a passive heat dissipation heat sink 1300 incorporating a series of super-Planckian photonic crystal (SP-PC) radiators 1381 according to one embodiment. The super-Planckian photonic crystal (SP-PC) radiators 1381 are attached to a parabolic substrate and cold plate 1306, and a focusing rod or lens 1308 attaches the thermal metasurface 1320 to an optical coupling that routes the thermal radiation emitted by the SP-PC radiators 1381 into a fiber optic bundle 1370, as illustrated in FIGS. 20-23. The heat dissipation heat sink 1300 also includes a super-Planckian (SP) thermal compound similar to material or compound 782b described above.

[0084] The radiator 1380 includes a woodpile photonic crystal 1381 mounted on the parabolic surface of the cold plate 1306, and a focusing rod 1308 having a lower convex surface at its bottom and an upper planar or emitter surface 1320 at its opposite top. In one embodiment, the lower convex surface at its bottom provides a focal point for the concentrated super-Planckian thermal radiation (SPTR) emanating from the photonic crystal. The upper planar surface of the emitter surface 1320 defines the apex of the top of the focusing rod 1308 and includes a surface, such as a thermal metasurface, to collimate, focus, and condition the concentrated thermal radiation from the heat source into the fiber optic bundle.

[0085] The large-scale structure of the photonic crystal unit cell is non-square with any length in any dimension, and the Planck number (n x or n y These parameters can be varied as long as the length of the layers is adjusted for the change in length. y The odd layers share the component L xWhen L is large enough in either dimension, the angle of curvature can be used to give a coarse-grained parabolic curve of the final effective SPP-RHS structure, allowing the emitted radiation to be focused along one or more axes. In such an embodiment, a focusing rod, or sphere, is used as a focus for an array of super-Planckian thermal radiation emitting dissipative heat sink elements arranged over a parabolic substrate (e.g., parabolic fins) or cold plate, and acts as an optical coupling to direct the concentrated incident radiation away from the thermal source and into a thermal reservoir provided by the low temperatures of the local universe outside the Earth's atmosphere. In some embodiments, the shape, spacing, material, or dopants of the bulk refractory material defining the top layer of the PC lattice unit cell can be altered to further enhance the preference and emission angle of the thermal photons, or to further tune the amplitude, deflection, and phase of the thermal photons to subject them to focusing schemes, direct them to distant locations in the environment via waveguides, line-of-sight optics, or light pipes.

[0086] 29 shows a schematic diagram of a server enclosure 1401 including a passive thermal dissipation heat sink device 1400 in an embodiment. The passive thermal dissipation heat sink device 1400 includes a thermal pixel array 1495 in the bulk material of a cold plate 1406 to measure or visualize the temperature of a heat source (chip package) 1430 through an infrared-transmitting inset 1496. The thermal dissipation heat sink device 1400 further includes a SP-PC 1481 attached to the top of the cold plate 1406 and configured to emit SP thermal radiation from the top of the server enclosure 1401.

[0087] 30 shows a schematic diagram of a server enclosure 1501 including an active thermal dissipation heat sink device 1500 in an embodiment. The passive thermal dissipation heat sink device 1500 includes a cold plate 1506 made of a bulk material such as SiC, and a SP-PC 1581 attached to the top of the cold plate 1506, which emits spatially coherent SPFF (super-Planckian far-field) thermal radiation from the top of the server enclosure 1501, and includes a high thermal conductivity single crystal layer 1597 at the bottom of the cold plate.

[0088] 31 shows a schematic diagram of a server enclosure 1601 including an active thermal dissipation heat sink 1600 in an embodiment. The device 1600 includes a thermoelectric (TEC) cooler attached to the bulk material (SiC) of a cold plate 1606 that includes a high thermal conductivity single crystal layer 1697 at the bottom of the cold plate, and a radiator SP-PC that emits spatially coherent, atmospheric window conditioned, super-Planckian thermal radiation (SPTR).

[0089] 32 shows a schematic diagram of a server enclosure 1701 including a passive thermal dissipation heat sink 1700 according to an embodiment. The device 1700 includes fins 1798 attached to a finned metallic or ceramic cold plate 1806 perpendicular to a heat source 1730, the fins 1798 being configured to maximize the radial field of view of each fin to the sky.

[0090] 33 shows a schematic diagram of a server enclosure 1801 including an active thermal dissipation heat sink device 1800 in an embodiment. The device 1800 radiates broadband super-Planckian thermal radiation (SPTR) to a powered heat exchanger (thermoelectric cooler) with a cold reservoir (the cold side of the thermoelectric cooler acts as a broadband super absorber), and the hot side of the heat exchanger (the capacitor) is cooled either passively or via an atmospheric window super-Planckian emitter such as a SPTR photonic crystal (PC) 1881.

[0091] 34 shows a schematic diagram of a server enclosure 1901 including a passive thermal dissipation heat sink device 1900 in an embodiment. The device 1900 utilizes powered airflow within the enclosure 1901 to dissipate heat, for example by convection cooling across a segmented (e.g., finned) cold plate 1906, the fins of which are thermally connected to the base of the cold plate (including a high thermal conductivity single crystal layer 1997) by heat pipes, the ends of which are connected to a super-Planckian atmospheric window tuned photonic crystal 1981. The emitted radiation passes through a transparent window or transparent lens mounted within the enclosure 1901.

[0092] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A cooling system for a heat source, the cooling system comprising:

1. A heat sink subsystem comprising: an energy converter configured to generate radiation from thermal energy absorbed from a heat source; a heat sink subsystem including a radiator configured to emit the radiation generated by the energy converter out of the heat sink subsystem, wherein received light facilitates the emission of the radiation; a sensor subsystem thermally coupled to the heat source, the sensor subsystem configured to output one or more signals indicative of a temperature distribution of the heat source; a control subsystem configured to control one or more characteristics of the heat sink subsystem based on the one or more signals indicative of a temperature distribution of the heat source; A cooling system comprising:

2. A cooling system as described in claim 1, wherein the radiation includes light.

3. The cooling system of claim 1, further comprising an optical subsystem configured to transmit light to the radiator.

4. A cooling system as described in claim 1, wherein the energy converter includes one or more carbon nanotubes.

5. A cooling system as described in claim 1, wherein the radiator includes a two-dimensional arrangement of emitter elements, each emitter element configured to emit the radiation generated by the energy converter outside the heat sink subsystem.

6. The cooling system described in claim 5, wherein the control subsystem configured to control one or more characteristics of the heat sink subsystem based on the one or more signals indicating the temperature distribution of the heat source includes the control subsystem configured to control one or more characteristics of specific emitter elements of specific emitter elements in the two-dimensional arrangement in accordance with the temperature distribution of the heat source.

7. The cooling system of claim 1, wherein the sensor subsystem is integrated with the heat sink subsystem.

8. The cooling system of claim 1, wherein the heat sink subsystem further includes a cold plate positioned between the energy converter and the radiator.

9. A method for cooling a heat source, comprising: The method comprises: generating radiation from thermal energy absorbed from the heat source by an energy converter in a heat sink subsystem; emitting the radiation generated by the energy converter out of the heat sink subsystem by a radiator of a heat sink subsystem, wherein received light facilitates the emission of the radiation; outputting, by a sensor subsystem thermally coupled to the heat source, one or more signals indicative of a temperature distribution of the heat source; controlling, by a control subsystem, one or more characteristics of the heat sink subsystem based on the one or more signals indicative of the temperature distribution of the heat source; A method comprising:

10. The method of claim 9, further comprising transmitting light to the radiator by an optical subsystem.

11. The radiator comprises a two-dimensional arrangement of emitter elements; radiating the radiation out of the heat sink subsystem by a radiator of the heat sink subsystem, 10. The method of claim 9, comprising emitting the radiation generated by the energy converter out of the heat sink subsystem by one or more emitter elements of the two-dimensional arrangement of emitter elements.

12. The method described in claim 11, wherein controlling by the control subsystem the one or more characteristics of the heat sink subsystem based on the one or more signals indicating the temperature distribution of the heat source includes controlling the one or more characteristics of particular emitter elements of the two-dimensional arrangement of emitter elements in accordance with the temperature distribution of the heat source.

13. The sensor subsystem is integrated with the heat sink subsystem; The method of claim 11 , wherein the heat sink subsystem includes a cold plate disposed between the energy converter and the radiator.

14. A cooling device for a heat source, comprising: The cooling device comprises: an energy converter configured to generate radiation from thermal energy absorbed from the heat source; a radiator configured to emit the radiation generated by the energy converter out of the cooling device, wherein received light facilitates the emission of the radiation; one or more sensors thermally coupled to the heat source, the one or more sensors configured to output one or more signals indicative of a temperature distribution of the heat source; At least one of the energy converter and the radiator has at least one characteristic that is controllable based on the one or more signals indicative of the temperature distribution of the heat source. A cooling device comprising:

15. The cooling device of claim 14, further comprising a light source configured to transmit light to the radiator.

16. A cooling device as described in claim 14, wherein the energy converter includes one or more carbon nanotubes.

17. A cooling device as described in claim 14, wherein the radiator includes a two-dimensional arrangement of emitter elements, each emitter element configured to emit the radiation generated by the energy converter outside the cooling device.

18. A cooling device as described in claim 15, wherein at least one of the energy converter or the radiator having the one or more characteristics controllable based on the one or more signals indicating the temperature distribution of the heat source includes specific emitter elements in a two-dimensional arrangement of the emitter elements having the one or more characteristics controllable in accordance with the temperature distribution of the heat source.

19. A cooling device as described in claim 14, wherein the one or more sensors include a two-dimensional arrangement of multiple sensors.

20. A cooling device as described in claim 14, further comprising a cold plate disposed between the energy converter and the radiator.

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